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Human Coronavirus HKU1: All You Need to Know

Mar 20 , 2025 | 8 min read

Recently, a case of Human Coronavirus HKU1 (HCoV-HKU1) infection was reported in Kolkata, drawing attention to this lesser-known but significant member of the coronavirus family. Typically circulating during winter and early spring, HCoV-HKU1 causes mild respiratory infections similar to the common cold but can lead to severe complications in vulnerable populations. Its recent detection in India has raised concerns and questions about its transmission, symptoms, and potential public health impact, especially in a post-COVID-19 landscape. In this blog, we’ll explore everything you need to know about HCoV-HKU1, including its origins and symptoms, prevention, and how its infection differs from COVID-19.

What is Human Coronavirus HKU1?

Human Coronavirus HKU1 (HCoV-HKU1) is a type of coronavirus that primarily affects the respiratory system. It was first identified in 2005 in patients with pneumonia and is part of the Betacoronavirus genus, similar to OC43, another common human coronavirus.

HKU1 is a seasonal virus, typically circulating in winter and early spring, and is known to cause mild respiratory symptoms like cough, runny nose, and fever. However, in elderly, people with weakened immune systems, and those with underlying conditions, it can lead to more severe complications, including pneumonia and bronchitis.

How Does HKU1 Coronavirus Spread?

HKU1 coronavirus spreads through respiratory droplets, contaminated surfaces, and close contact with infected individuals. Like other seasonal coronaviruses, it primarily transmits in colder months but can circulate year-round in some regions. The main transmission routes include:

Respiratory Droplets: When an infected person coughs or sneezes, tiny droplets containing the virus are released into the air. These droplets can be inhaled by others nearby, leading to infection.
Surface Contamination: The virus can survive on surfaces for a limited time. Touching contaminated objects, such as doorknobs, handrails, or shared items, and then touching the face—especially the nose, mouth, or eyes—can allow the virus to enter the body.
Close Contact: Spending time near an infected person, particularly in crowded or enclosed spaces, increases the risk of exposure. Households, public transport, and healthcare settings can contribute to the spread.

What are the Symptoms of HCoV-HKU1 Infection?

HCoV-HKU1 infection usually causes mild to moderate respiratory symptoms, similar to other seasonal coronaviruses. The severity of illness varies, with most people experiencing mild symptoms, while those with weakened immune systems, older adults, and infants may develop more serious complications.

Common Symptoms

Runny or stuffy nose – Often one of the first signs, similar to a cold.
Cough – Can be dry or produce mucus, depending on the severity of infection.
Sore throat – May be mild or more pronounced, particularly in the early stages.
Fever – Usually low-grade but can be higher in some cases
Fatigue – A general feeling of tiredness, sometimes lasting for several days
Headache – Common in viral infections due to inflammation and congestion.

Severe Symptoms (Less Common, Higher Risk in Vulnerable Groups)

Shortness of breath – Can occur if the infection spreads to the lower respiratory tract.
Chest discomfort – May be present in cases of bronchitis or pneumonia
Wheezing – More common in people with pre-existing respiratory conditions.
Pneumonia or bronchitis – Severe cases can lead to lung infections, especially in those with weakened immune systems, chronic lung disease, or other underlying health conditions.

Symptoms generally appear 2 to 5 days after exposure and can last for a week or longer. Most cases resolve on their own, but complications may arise in individuals with existing respiratory illnesses or immune deficiencies.

How is HKU1 Diagnosed?

HKU1 coronavirus is diagnosed using laboratory tests, as its symptoms closely resemble those of other respiratory viruses, including common cold coronaviruses, influenza, and even COVID-19.

PCR (Polymerase Chain Reaction) Test – This is the most accurate method for detecting HKU1 infection. A swab sample is collected from the nose or throat and tested for the virus’s genetic material. PCR testing is widely used in hospitals and research settings when confirmation of the virus is needed.
Respiratory Panel Tests – Multiplex PCR panels can simultaneously detect multiple respiratory viruses, including HKU1, in a single sample. These are often used in hospitals to identify the cause of severe respiratory infections, especially in patients with pneumonia or complications.
Serology Tests (Antibody Tests) – Blood tests can detect antibodies produced by the immune system in response to HKU1 infection. However, they are not commonly used for diagnosing active infections since antibodies take time to develop and remain present after recovery. These tests are more useful for studying past infections or population exposure.
Viral Culture – A laboratory technique where the virus is grown from a collected sample to confirm its presence. This method is rarely used for routine diagnosis because it is time-consuming and requires specialised facilities.
Antigen Tests – These tests detect viral proteins and provide quicker results than PCR tests. However, they are less sensitive and not widely used for HKU1 diagnosis.

Since HKU1 infections are typically mild, routine testing is not common. It is mainly performed in cases where a specific diagnosis is needed, such as for hospitalised patients with unexplained respiratory illness or during public health investigations of viral outbreaks.

How is HKU1 Infection Managed and Treated?

There is no specific antiviral medication for HKU1 coronavirus. Since it typically causes mild to moderate respiratory illness, treatment focuses on managing symptoms and supporting recovery. Most cases resolve on their own without medical intervention, but severe infections may require hospital care.

Home Care and Symptom Management

For mild cases, home care can help alleviate symptoms and promote faster recovery:

Adequate Rest – Resting allows the immune system to fight the infection more effectively. Overexertion can prolong recovery.
Hydration – Drinking fluids, such as water, warm broths, and herbal teas, helps prevent dehydration, especially in fever and excessive mucus production.
Over-the-counter medications – Pain relievers such as paracetamol can help reduce fever, headaches, and body aches. Decongestants or antihistamines may provide relief from nasal congestion.
Steam Inhalation and Humidifiers – Breathing in steam or using a humidifier can help loosen mucus and relieve throat irritation and congestion.
Gargling with Salt Water – Can soothe a sore throat and help reduce throat inflammation.
Avoiding Irritants – Staying away from cigarette smoke, strong odours, and pollution can prevent further irritation of the airways.

Hospital Treatment for Severe Cases

In cases where HKU1 infection leads to complications such as pneumonia or bronchitis, medical intervention may be necessary. Hospital treatments may include:

Oxygen Therapy – For patients experiencing breathing difficulties or low oxygen levels.
Intravenous Fluids – Given to patients who are severely dehydrated or unable to take fluids orally.
Mechanical Ventilation – In rare cases, patients with severe respiratory distress may require ventilator support.
Antibiotics (If Bacterial Co-Infection Occurs) – Although HKU1 is a viral infection, secondary bacterial infections such as bacterial pneumonia may develop, requiring antibiotic treatment.

How Can HKU1 Coronavirus Infection Be Prevented?

There is no vaccine for HKU1 coronavirus, so prevention focuses on reducing the risk of exposure and strengthening the body’s defences against respiratory infections.

Hygiene Practices

Frequent Hand Washing – Washing hands with soap and water for at least 20 seconds helps remove viruses that may be present on the skin. If soap and water are unavailable, an alcohol-based hand sanitiser with at least 60% alcohol can be used.
Avoiding Face Touching – The virus can enter the body through the eyes, nose, and mouth. Avoiding unnecessary face touching reduces the risk of infection.
Using Tissues or Elbows to Cover Coughs and Sneezes – This prevents respiratory droplets from spreading in the air and onto surfaces. Used tissues should be discarded immediately.
Regular Surface Disinfection – Frequently touched objects and surfaces, such as doorknobs, mobile phones, remote controls, and countertops, should be cleaned and disinfected regularly to prevent contamination.

Reducing Exposure to the Virus

Avoiding Close Contact with Sick Individuals – People showing symptoms of respiratory illness should be avoided where possible, especially in crowded places.
Wearing a Mask in High-Risk Areas – While HKU1 is not as widely tested as other coronaviruses, wearing a mask in healthcare settings or during peak flu seasons may help reduce exposure to respiratory viruses.
Improving Indoor Ventilation – Ensuring proper airflow in indoor spaces can help reduce the concentration of airborne viruses.

Strengthening Immunity

Maintaining overall health can lower the risk of severe illness from HKU1 and other respiratory infections:

Eating a Nutrient-Rich Diet – Consuming a balanced diet with plenty of fruits, vegetables, lean proteins, and whole grains helps support immune function.
Staying Physically Active – Regular exercise contributes to a stronger immune system and overall well-being.
Getting Enough Sleep – Lack of sleep weakens the immune system, making the body more vulnerable to infections.
Managing Chronic Conditions – Individuals with diabetes, asthma, or heart disease should follow their prescribed treatments to prevent complications if infected.

Since HKU1 infection is more common in colder months, taking extra precautions during winter and early spring can help minimise the risk of infection.

How is HKU1 Infection Different from COVID-19?

HKU1 and COVID-19 are both coronaviruses, but they differ in several ways, including severity, transmission, and impact on public health.

Virus Type

HKU1 – First identified in 2005, HKU1 is one of the four human coronaviruses that commonly cause mild respiratory infections. It is not a novel virus and has been circulating for years.
COVID-19 (SARS-CoV-2) – A novel coronavirus that emerged in late 2019, causing a global pandemic due to its high transmission rate and potential for severe illness.

Severity and Symptoms

HKU1 – Typically causes mild to moderate respiratory symptoms, such as cough, runny nose, sore throat, and fever. Severe cases are rare and mostly affect individuals with weakened immune systems or underlying health conditions.
COVID-19 – Symptoms range from mild to severe, with some cases leading to pneumonia, organ failure, or long-term complications. Loss of taste and smell, a common symptom of COVID-19, is not typically associated with HKU1 infection.

Transmission

HKU1 – Primarily spreads through respiratory droplets, close contact with infected individuals, and contaminated surfaces. It is seasonal, peaking in winter and early spring.
COVID-19 – Spreads more efficiently, including through airborne transmission in enclosed spaces. Unlike HKU1, it has caused widespread outbreaks beyond seasonal patterns.

Treatment and Prevention

HKU1 – No specific antiviral treatment. Supportive care helps relieve symptoms, and cases usually resolve on their own.
COVID-19 – Specific treatments such as antiviral drugs and monoclonal antibodies are available for severe cases. Vaccines have been developed to reduce infection rates and severe outcomes.

HKU1 infection is generally mild and self-limiting, whereas COVID-19 has had a significant global impact due to its higher transmission rate and potential for severe disease.

Consult Today

HKU1 may not be as widely known as COVID-19, but it can still cause complications in vulnerable individuals. A timely consultation with a pulmonologist can help determine the cause of persistent respiratory symptoms and provide appropriate management. At Max Hospital, specialists in respiratory medicine are available to assess, diagnose, and guide treatment for respiratory infections. Whether it’s a lingering cough, breathing difficulties, or concerns about viral infections, a consultation can offer clarity and the right course of action. Book an appointment with a pulmonologist at Max Hospital for a thorough evaluation and care.